package oj0424.oj0424_03;

import java.math.BigInteger;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        BigInteger bi = BigInteger.ONE;
        for (int i = 2; i <= n; i++) {
            BigInteger t = BigInteger.valueOf(i);
            bi = bi.multiply(t);
        }
        System.out.print(bi);
        sc.close();
    }
}
